Not applicable.
(1) Field of the Invention
The invention relates to the removal of coatings, such as paint, from a substrate and is directed more particularly to removal of paint, or other such coatings, in air, without damage to the substrate.
(2) Description of the Prior Art
It is known to remove paint from substrates by utilizing ultrasonic fields to produce micron-sized vapor (or cavitation) bubbles which impinge against the paint. The microcavitation allows for removal of the paint from the substrate without damaging the substrate. This is taught by U.S. Pat. No. 5,681,396. Inasmuch as micron-sized cavitation bubbles are used to remove the coating, the process works well underwater. However, to adapt the process to surfaces in the air requires the application of water, as by jets of water, to immerse the coated surface. In such procedures, the amount of water required is quite large and the used water is contaminated with the removed paint or other coating material, all hereinafter referred to as xe2x80x9cpaintxe2x80x9d.
There is thus a need for a method for acoustic cavitation-based paint removal in air, wherein the substrate is not damaged by the cavitation, a relatively small quantity of water is required, and the contaminated water run-off is minimal.
An object of the invention is, therefore, to provide a method for removing paint from a substrate without damage to the substrate.
A further object of the invention is to provide such a method wherein an acoustic field causes formation of micron-sized vapor or cavitation bubbles which are impinged upon the paint surface to cause removal of paint therefrom, wherein the process requires relatively small quantities of water and produces a relatively small run-off of contaminated water.
With the above and other objects in view, as will hereinafter appear, a feature of the present invention is the provision of an apparatus and method for removing paint from a substrate disposed in air. The apparatus includes a sponge capable of having a fluid therein. The sponge has a first surface that can be placed in contact with the coating. High and low frequency transducers are positioned in contact with the second surface of the sponge. Activation of the transducers generates cavitation at the surface of the coating for removing the coating.
The method includes the steps of providing a sponge having a first surface for contact with the substrate, providing ultra sonic transducers in contact with a second surface of the sponge opposite from the first surface, saturating the sponge with water to provide a path of water extending from the transducers to the substrate, and activating the transducers to generate (i) a low frequency acoustic field; and (ii) a high frequency acoustic field; and thereby (iii) micron-sized vapor (or cavitation) bubbles which impinge upon the paint on the substrate to remove the paint from the substrate as taught by U.S. Pat. No. 5,681,396.
The above and other features of the invention, including various novel details of construction and combinations of steps, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method embodying the invention is described by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention.